The engine was designed to produce a total of 4,520 indicated horsepower (3,370 kW) which gave the ship a speed of 10 knots (19 km/h; 12 mph).

[5][6] During a pre-commissioning test of her steam engines off Ferrol on 31 March 1866, Tetuán suffered damage when she struck rocks on the Palma shoal.

She got underway from Ferrol on 6 April 1866 and proceeded to Cádiz, where it was discovered that her hull damage was greater than previously thought.

She instead was assigned to duty in the Caribbean and departed Cádiz on 22 December 1866 bound for Havana[4] in the Captaincy General of Cuba.

[4] Tetuán was at Cádiz when the Glorious Revolution began on 19 September 1868, and she joined the rebel naval forces commanded by Juan Bautista Topete.

[4] She entered the Arsenal de Cartagena for modernization, during which several large-caliber rifled muzzle-loading Armstrong guns were installed, an armored redoubt was constructed on her deck, and almost all of her rigging was removed.

At the time, Tetuán was lying disarmed at the Arsenal de Cartagena, awaiting the installation of new guns, and came under the control of the Cantonalists, who hastily returned her to service.

Tetuán, the armoured frigate Numancia, and the paddle gunboat Fernando el Católico departed Cartagena on 25 August 1873.

[9] Tetuán, Numancia, and the armoured frigate Méndez Núñez bombarded Alicante on 27 September 1873, firing a combined 500 rounds.

[4] At the beginning of October 1873, Tetuán and Fernando el Católico got underway from Cartagena and, without any opposition from the central government fleet, conducted landings at Garrucha, Cuevas,[disambiguation needed] Mojácar, and Torre-Pacheco.

[10] News of the passage of this squadron through Almería reached Cartagena on 9 October, and the Cantonalist forces made plans to attack it.

[12] Later, during the night of 10–11 October, he ordered his ships to raise sail, probably to economize on their use of coal, and a strong north wind blew his squadron offshore and eastward to a position east of Portmán, Spain.

[11][12] At 11:30, the two squadrons sighted one another, with the Cantonal ships 3 nautical miles (5.6 km; 3.5 mi) due south of Cape Agua and Lobo's squadron about 6 nautical miles (11 km; 6.9 mi) to the south in waters east of Cape Negreti,[12] and the Battle of Portmán began.

[12] Vitoria broke off to chase Numancia, leaving Almansa, Carmen, and Navas de Tolosa to face the approaching Tetuán and Méndez Núñez.

[12] Almansa, Carmen, and Navas de Tolosa were steering toward Cartagena in the wake of Numancia and Vitoria,[12] putting them on a converging course with Méndez Núñez.

[12] Passing Almansa, Carmen, and Navas de Tolosa, she steamed toward Diana, but upon discovering that the other Cantonal ships had fled, she turned around off Cape Negreti and slowly steamed back towards Cartagena, again engaging in succession Carmen, Almansa, and Navas de Tolosa.

[11][12] With shots from both sides passing through her topsails, Thétis maneuvered to extricate herself from her predicament while Tetuán took advantage of the situation to steam to the west of Vitoria, closer to the guns of Cartagena's coastal forts.

[12] Vitoria scored hits that passed right through Tetuán and then, although the central government claimed she sustained no damage, broke off the engagement, steamed out to sea, and went dead in the water for at least an hour.

[11] Tetuán, Méndez Núñez, 'Numancia, and Despertador del Cantón departed Cartagena on 17 October 1873 to transport several Cantonal leaders to Valencia and Barcelona.

[18] Like Lobo, however, Chicarro avoided combat, despite the arrival of Zaragoza, which gave him a squadron that included two armored frigates.

[4] People crowded the docks to watch the fire until some of Tetuán′s smaller stores of ammunition and gunpowder began to explode.